Metallic-vapor lamp.



NST.

METALLI APPLICATION NER C VAPOR LAMP.

FILED Patnted 0a., 23, 1917.

l/VVE/VTOH v WALTHER HERA/6T .Armem 7 BY I mm I WITNESSES EDSTATESWALTHER NERNS'I, OF BERLIN, GERMANZ ASSIGNOR TO DEUTSGHE GASGL'U'HLICHTAKTIENGESELLSCHAFT (AUERGESELLSCHAFT), 0F BERLIN, GERMANY, CORPORA- mmor GERMANY.

METALLIC-VAPOR LAMP.

Patented Oct. 23,1917.

Application filed February 2, 1914. Serial No. 815,869.

To all whom it may concern:

Be it known that I, l/VALTHER NERNST, a subject of the German Emperor,residing at Berlin, Germany, have invented a new and useful Improvementin Metallic-Vapor Lamps, of which the following is a specification. v

My invention refers to metallic vapor lamps, that is to lamps containingsome suitable metal and provided with a space within which the vapor ofsuch metal becomes incandescent when the lamp is suitably actuated bythe necessary electric current.

The object of my invention is to provide a metallic vapor arc lamp inwhich that part of the lamp which. furnishes illumination during itsoperation, contains, before ignition, gases (or air) which, by reason ofthe seething and boiling of the metal, for instance, mercury, duringsaid operation, are driven completely out of the illuminating space,into an auxiliary chamber forming a part of said space, or in the caseof air into the atmosphere, and are prevented from reentering by thecontinued boiling of the metal, but when the lamp is extinguished, againenter into the illuminating space.-

Before the lamp is started, the illuminating space contains any suitablegas, for instance argon, or it may be filled with air and in such lattercase, this space communicates with the atmosphere. For the purpose ofignition the vapor producing metal is caused to actively give off saidvapor in any convenient manner. For this purpose mercury constitutes avery suitable metal, although the invention is by no means limited tomercury, and for convenience of description mercury, will be referred toas the metal used in the particular embodiments therein specificallydescribed. Other metals which may be used are zinc, cadmium and alloysof mercury with these metals, lead, etc., especially when closed lamps,filled with neutral gases are used. This vapor crowds out the gases orair which are in the illuminating space so that the plane of demarcationbetween the mercury vapor and the gas or air lies entirely outreferredto or with air; this space acts as a cooler.

The cooling effect must not be too great in order that the vapor columnbetween the illuminating space and the gases crowded out, may be longenough to prevent the back diffusion of gases toward the illuminatingmeans of a flame or by electrical means.

In the cases of lamps which contain neutral gases which neither combinewith or attack the vapor forming metal nor the anode, which latter maybe made of other metal, vaporization can be started in such a way thatan arc is first started in said gases (rare gases such as argon and neonare especially suitable for this), which are will then without anyspecial heating arrangement, supply sufiicient heatto maintain thenecessaryv vaporization and drive back the gases. The starting of theare may be done in any wellknown manner, for instance by tilting thelamp as is done in the case of Cooper-Hewitt lamps.

In lamps which are provided with their own special heating arrangementsuch arrangement may be either wholly or partially dispensed with assoon as the arc becomes stable and is itself able'to compensate for theloss of heat.

In the drawings Figure 1 represents one form of lamp embodying myinvention and Fig. 2 and Fig. 3 modified forms thereof.

Referring to Fig. 1 the illuminating tube has free communication withthe atmosphere. The cooler k is an upwardly directed tube which has anexpansion near its top; the condensed metal drops back toward themercury electrode 6. The preliminary heating before lighting, which maybe started The illuminatingspace, as also Fig. 2 illustrates a lamp,which is provided with a special space through which the gases may bepressed by vaporizing the electrode material (mercury is so-shaped, e.g'., U-shaped, t at mercury may then collect therein. This brings abouta closure between the vapor space Z, and the gas or air space whichprevents excessive argon or, better pressure fluctuations. a and 6represent the electrodes,'small vessels fille with mercury.

Fig. 3 illustrates a modifie form of lamp which is closed oil from theatmosphere and contains neutral gases as e. 9., attenuated still, neon.The auxiliary space is indicated by m and the illuminating space, asbefore,'by Z. This lamp can be started uplby a high tension impulse. Inthis lamp the cathode only consists of vaporizable material (mercury),for the anode, iron, etc., may be used. v The lamps are made from glassof very high heat resistance or better still of quartz. When I saynormally in the claims I refer to the condition of the lamp when it isnot ,being operated. I

I claim: r "1. A metallic vapor lamp comprising a receptacle having anilluminating space, an

auxiliary said space,

chamber communicatmg with and a cathode of vaporizable metal, the spacewithin the receptacle being normally at substantially atmosphericpressure. I

2. A metallic vapor lamp comprising a receptacle having an illuminatingspace, an auxiliary chamber, a cooler which connects illuminating spaceand auxiliary chamber and normally has a free passage therethrough, anda cathode of vaporizable metal and which I operation of the lamp,

within the receptacle, the free space within the entire receptacle beingnormally filled with a rare gas.

, 3(A metallic vapor lamp comprising a receptacle having an illuminatingspace, an auxiliary chamber, a cooler between illuminating space andauxiliary chamber and connected with both, and a cathode of vaporizablemetal the space within the recepan inert gas. The improvement in the artof operat- 5. ingmetallic vapor lamps having a vaporizable metalelectrode which comprises starting the are through a body of inert gaswhich is in contact with the cathode and in then causing said gas to bepressed substantially completely out of the illuminating space of thelamp by the vaporized cathode metal.

In testimony whereof, I have hereunto set o my hand in the presence oftwo subscribing wltnesses.

WALTHER NERNST. Witnesses WoLnEMAR HAUPT, HENRY, HASPER.

